Rusty Heller is a nightclub performer who has her eyes set on a better life for herself which, in her case, means lots more money. She sets her eyes on mobster Charles 'Pop' Felcher who has his own ambitions: with the recent arrest of Al Capone on tax evasion charges, he sees himself taking over as the top mobster in Chicago. When Felcher shows little interest in her, she settles for his lawyer, Archie Grayson. Felcher eventually comes around but Rusty starts to play a dangerous game when she decides to make money off Felcher and the Capone mob by selling both of them.

When a small-time hoodlum is apparently killed by Eliot Ness during a raid, the man's teenage son, Nicky Bousso, tries to kill him. Ness realizes that Nicky is no hood and tries to be nice, but the kid is persistent. When ballistics confirm that the man was killed before the raid took place, Nicky thinks Ness is just making it up. Nicky gets a job cleaning cars at his father's former place of work, a taxi company owned by Gus Marco.